Article bending machine



May 4, 1965 E. M. WISHING 3,131,331

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United States Patent O 3,181,331 ARTlCLE BENDENG MACHINE Eugene M. Wishing, Philadelphia, Pa., assigner' to l-T-E Qircuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed .lune 27, 1962, Ser. No. 205,611 3 Claims. (Cl. 72-2l5) My invention relates to an article bending machine, and more particularly to a machine incorporating a rotary sweep capable of radially varying to follow a parabolic or similar contour established by a backup form, so as to bend an elongated tube in accordance with the contour of the backup form.

ln many areas of mechanical fabrication, it is necessary to impart a curved shape to an elongated member with a minimum of effort, expense, maximum yield, and optimum reproducibility. A typical example is the quantity fabrication of parabolic antenna structures, wherein the antenna backing structure is formed of an appropriately interconnected array of tubular elements having a parabolic concavity corresponding to the desired antenna conguration. The accurate fabrication of such antenna structures requires that the individual parabolic tubes be bent to a high degree of accuracy. The fabrication of such tubes should preferably be performed in a manner insuring the necessary accuracy without requiring excessive machine costs or manpower requirements.

One method of bending tubes presently practiced is to longitudinally pass the tubes through an array of three rollers, two of the rollers being stationary and located at one side of the tube and the third roller being located at the other side of the tube, longitudinally intermediate the first -two rollers. The third roller is manually moved transverse to the direction of tube travel, thereby imparting a contour to the tube in accordance with the transverse displacement between the third roller and the set of stationary rollers. inasmuch as the proper movement of the third roller is dependent upon the skill and manual dexterity of the particular operator, this method suffers from high reproduction costs, uncontrolled repeatability, high scrap factor and need for undetermined amounts of re-work to obtain the desired shapes.

A somewhat modied arrangement of the basic threeroll method has been to establish a numerically controlled machine tool by -tape-controlling the movement of the third roller. This system suffers from the disadvantage of excessively high initial costs, and the need for a separate control tape for each shape and material being formed.

Another method of the prior art is to stretch the tube being bent across an appropriately contoured master form. This method suffers from high initial machine costs, excessive setup cost for changing shapes, and a fairly high scrap factor.

My invention avoids the above-discussed disadvantages of the prior art by utilizing an adjustable backup form, against which a forcibly driven arm presents the tube being bent. That is, the backup structure is adjusted to partake of the desired tube configuration to be formed (as adjusted for spring-back of the particular material being bent), and the tube is then worked against the smooth curve of the adjustable backup. The working of the tube against the backup is effected by a rotary sweep capable of varying in the radial direction in accordance with the contoured configuration of the backup structure. That is, the actuating mechanism of the arm is designed to simultaneously move in a rotary direction between the extremes of the adjustable form, and move in a radial direction transverse to its rotary sweep.

In the particular embodiment illustrated, a hydraulic drive means is shown. Alternatively, an air drive may be used. Such drive means advantageously permit the easy ldll Patented 'll/lay 4, l965 ice variation of the two-directional feed by bleeding one line off the other. The tubing, or any other elongated length of material within the capacity of machine, is formed by the pressure of the follower urging the tube against the adjustable backup form during the translation of the follower as it moves along the form, motivated by the hydraulically driven arm. The follower is preferably contoured to contain the cross-section of the article being bent, while permitting a small clearance gap between the article and the backup form to prevent crimping during bending. Also the follower is connected in a manner readily permitting interchangability for other sizes corresponding to other cross-sections of the material being bent.

lt is therefore seen that the basic concept of my invention resides in the use of an adjustable backup form, a follower means forcibly presenting the article being bent against the backup form, and a follower drive means having simultaneous rotary sweep and transverse motion, to thereby forcibly impart the requisite bending force to the article being urged over the surface of the backup form.

It is therefore a primary object of this invention to provide a bending machine for the efficient production of curved tubing, with a high degree of reproducibility.

Another object of this invention is to provide a machine for rapidly bending a plurality of similarly contoured tubes with a high degree of reproducibility, and having provision for changing the tube bend contour with a minimum of time, effort and expense.

An additional object of this invention is to provide a bending machine having an adjustable backup form and a pressure-actuated drive means to forcefully move a follower means over the contour of the backup form, whereby the article being bent is urged over the surface of the backup form.

A further object of this invention is to provide an article bending apparatus including an adjustable backup form secured to a platform, a follower means urging an article being bent against the backup form, and a drive means moving about and along the platform to effect movement of the follower means over the backup form contoured surface.

Still another object of this invention is to provide such an article bending apparatus in which the drive means is hydraulically actuated to controllably impart a rotary sweep motion and transverse motion to the follower means, such that the rotary sweep motion overcomes the transverse motion of the drive means.

Still an additional object of this invention is to provide such an article bending apparatus in which the adjustable backup form comprises a plurality of adjacent stops appropriately fastened to channel grooves in the platform and positioned to collectively assume the contour of the backup form.

Still a further object of this invention is to provide such a backup form having an elongated member extending between adjacent surfaces of the individual stops to form a -smoothly-contoured surface in accordance with the adjustable positions of the individual stops.

These as well as other objects of my invention will become apparent after reading the following descriptions of the accompanying drawings in which:

FlGURl-E l is an overall perspective View illustrating a preferred embodiment of my invention.

FIGURE 2 is a partial perspective view as seen from thev contoured surface of the adjustable backup form, and particularly illustrating the manner in which the article being bent is urged to take the contour of the adjustable backup form.

FIGURES 3 and 4 are plan and elevation views respectively of the article bending apparatus of FIGURES l and 2.

FIGURES 5 and 6 are plan and cross-sectional views of a typical backup stop, which may be used to form the adjustable backup form of my invention.

FIGURES 7 and 8 are plan and elevation views respectively of a preferred article clamping means used in conjunction with the apparatus of my invention.

FIGURE 9 illustrates the manner in which the smoothing contour means may be stretchably fastened.

FIGURES 10 and 11 are plan and cross-sectional views respectively illustrating the manner in which the length of the drive means arm may be varied.

FIGURE 12 is a cross-sectional view of the arm drive means at its transverse actuated end, indicating the manner in which its transverse motion is facilitated.

FIGURE 13 shows a typical hydraulic circuit which may be used to impart the dual-mode movement to the drive means.

Referring to the figures, and particularly FIGURES 1-4, article bending apparatus 20 comprises a table-like platform appropriately elevated and supported by structural members, typically shown by 21-24. Platform 30 includes a plurality of longitudinal channels 31-39 extending between its opposite end extremes -41. Backup stops which may typically be cast-iron castings are appropriately positioned within channels 31-39, `such that their front surfaces 52 collectively establish the contour desired of the material to be bent. Although the longitudinal channels are typically shown as nine in number, an alternative number or spacing of such channels may be employed in accordance with the particular adjustable backup form contour to be generated by individual backup stops 50. This contour will vary somewhat from the actual contour of the tube 100 to be bent in accordance with the spring-back adjustment for the particular tube material. The manner in which individual stops 50 are interconnected to table 30 via the channels 31-39 will be subsequently set forth in conjunction with the discussion of FIGURES 5 and 6.

Contour smoothing means 60, which may typically be a 1/8" stainless steel strap, is appropriately stretched across the surface formed by the adjacently arranged ends 52 of individual stops S0 to establish a smooth curve contoured in accordance with the positioning of the individual backup stops 50. The manner in which strap 60 is ailxed to table 30 will be subsequently set forth in conjunction with the discussion of FIGURE 9.

Follower means 70, which traverses the path established by members 50 and 60, comprises a roller appropriately contoured to contain the cross-section of tube 100 and present it to contoured surface 60. Follower 70 is preferably dimensioned to leave an air gap, as for example .002", between tubular member 100 and backup form surface 60 as follower 70 traverses its path. Such an air gap prevents crimping of the tube 100 during bending. Follower means 70 is connected via shaft 72 to the forwardly extending end portion 82 of drive means arm 80. Shaft '72 is interconnected to drive means forward member 82 via bearing rings '74, 76 and '78 to facilitate rotative motion of follower 70 during the rotary sweep of drive means 80, and is secured to shaft 72 in a manner which permits its easy removal and replacement by a diiferently contoured follower 70, appropriately dimensioned in accordance with the cross-section of the particular article to be bent. Drive means arm 80 has two simultaneous modes of movement, one being a rotary sweep about vertical axis 25, and the other being a transverse movement along its longitudinal axis 35; the latter movement being governed by the engagement of follower means 'i0 and contoured surface 60. The transverse movement of drive means arm 80 is illustratively shown actuated by a hydraulic cylinder 90 appropriately interconnected to series connected longitudinal arm sections 83-86 to provide transverse movement of the shaft. As a preferred feature of my invention the individual sections 83-85 are readily detachable to vary the length of the arm 80, in

accordance with the particular curve to be generated. The rotary sweep of the drive means is imparted by a conventional type of rotary torque actuating unit 95. The most forwardly extending portion of shaft section 82 is raised above top surface 30 by bearing housing 87 containing a plurality of ball bearings 83, which ride along table 30 during the rotary sweep of the drive means. It has been found that the use of such ball bearings readily facilitates the rotary sweep, without being interfered with by the longitudinal channels 31-39, as would be the case with wheels. Rotary torque actuator unit 9S and hydraulic cylinder 90 are appropriately interconnected, as will be subsequently set forth in conjunction with the discussion of FIGURE 13, to impart the necessary composite movement to drive means arm `80.

The actuating portion of drive means 80, including hydraulic cylinder 90 and rotary torque actuator unit 95 is supported by table-like surface 61, appropriately supported by support members such as 61-69.

The operation of the tube bending machine 20 is as follows:

Individual stops 50 are first positioned and fastened to establish the requisite contour of the adjustable backup form. Contour smoothing means, or steel strap `60, is stretched over the adjacently arrayed forward portions 52 of the individual backstops to form a smooth curve. Tube 100 is then clamped at one of its ends 102 by clamping means 56, in the manner to be subsequently discussed in conjunction with FIGURES 7 and 8. Drive means 80 is then positioned (in the manner to be set forth in conjunction with the discussion of FIGURE 13) to place follower 70 against contoured surface 60, at tube end 102, as shown by the dotted position 35 of FIGURE 3. The hydraulic actuating means 120 simultaneously rotates arm about axis 25 while urging transverse movement of follower 70 along axis 35, towards backup form surface 60. The arm 80 will translate along the path determined by 60, to the end position 35 of FIGURE 3. The tubing 100 (or any other bar-type material), within the capacity of the machine, is formed by the pressure of the follower 70 forcing the work against adjustable backup surface 60 and the translation of follower 70 as it moves along the form motivated by arm 80. The tube 100 is then released and examined to ascertain whether any adjustments need be made in the positioning of stops 50 to compensate for material spring-back. The particular hydraulic actuating means of cylinder and rotary torque actuator g5 are determined by the properties of the material being bent, with appropriate pressure adjustment such that the sweep motion overcomes the transverse movement of arm 80. In a typical illustrative embodiment designed to bend aluminum tubing, hydraulic actuated arm 80 had a capability of 280 of rotary motion, being actuated `by rotary torque actuator rated at 6200 inch pounds at 1,000 p.s.i. Cylinder 90 had a twelve-inch stroke and 3% bore and a clamping capacity of 8,000 pounds, and nominally operated at 1,000 p.s.i. Such a machine has demonstrated an ability to bend 7 lengths of tubing within 45 seconds and with an overall accuracy of 0.010. Thls embodiment of my invention has been constructed at a `cost approximating one-tenth the cost of presently available1 machines capable of accomplishing comparable resu ts.

FIGURES 5 and 6 typically illustrate the manner in which the individual backup stops 50 may be xedly secured to their respective channel of table 30. Backup stop 50 contains an elongated slot 51, having a socket head screw 53 and nut 55, respectively, at its top surface. Screw 53 engages T-slot nut 54 contained within its respective channel, i.e. such as 32. A plurality of T-nuts 54 are disposed within each of the channels .3l-39, to mate with appropriately positioned backup stops 50, as needed. It is thus seen that the relative engagement of members .S3-54 permits the relocation of individual contour formlng backstops 50, in a relatively easy manner.

FIGURE 7 illustrates a preferred means for clamping tube end 102 against the backup form. Clamp 56 may be aiiixed to its respective channel such as 34 in a manner analogous to that shown in conjunction with individual backstop 50, and is shown containing elongated slot 51 and associated screw and nut 53', 54. Screw 53 mates with a T-slot nut (not shown) in its respective channel. Projecting upwards from the forward end 57 of clamp 56 is a coarsely knurled portion S8. By urging knurled portion 58 against tube end 102 to tight engagement with surface 60, tube 100 is maintained against backup form 60.

FGURE 9 indicates the manner in which steel strap 60 may be stretched against the forward surfaces 52 of individual backup stops 50. Steel strap 60 contains apertures 91, 92 at its ends, which are interconnected to support member 93 via socket head screws 941, 95'. Support member 93 is connected to bracket 96 Via adjusting screw 97, with a gap d between the end of support member 93 and bracket 97. By tightening screw 97, gap d is decreased, thereby stretching steel strap 60, to establish a smoothly contoured surface across the adjacently arrayed ends 52 of the individual stops 50. Bracket 97 is appropriately affixed to table 30, as for example in the manner members 50 and 56 are afiixed.

FIGURES l() and ll illustrate a preferred interconnection of two individual arm 80 sections, such as 84;, 85, to provide the aforesaid adjustment of overall arm length. The ends of such adjacent members 84, 85 contain iianges 103, 104 having mating openings 105 peripherally disposed thereabout to receive stripper bolts 106 secured by lock nuts 107 and washers 108. As best seen in FIGURE 11, shaft section 85 preferably has a square cross-section. This serves to offer increased resistance to twisting, as the tube is being bent.

FIGURE l2 illustrates the manner in which longitudinal movement of the drive means shaft S6 is facilitated. Ball bearing pairs 109-112 engage that portion of shaft 36 interconnected to hydraulic cylinder 90, which undergoes the transverse movement. Wheels 113 are provided to facilitate the rotary scan of the drive means about its support table 61.

FIGURE 13 illustrates a typical hydraulic circuit 120 which has demonstrated successful operation as the basic actuating force for the dual mode drive of arm 80. The prime hydraulic source is generated by pump 121 driven by motor 122, and operating in conjunction with fiuid reservoir 123. Pump 121 is interconnected to the input port 124 of pressure-compensated flow regulator 125, via series connected lines 128, 129, having check valve 130 interconnected therebetween. Pressure compensated flow regulator 125 has a regulated output port 126 interconnected to the transverse movement actuating means, and bypass port 127 interconnected to the rotary sweep movement actuating means.

Referring first to the transverse movement actuating means, regulator port 126 is connected to valve 127 via series connected feed lines 128', 129', with relief valve 130 connected therebetween. Valve 127" may typically be a four-way lever-operated three-positioned detent-type valve, having provision for manual adjustment of the arm 30 position. As connected in the manner shown in FIG- URE 13, the piston 98 of hydraulic cylinder 90 will be moved in the direction shown by the arrow. Hydraulic feed line 128 is shown connected to input valve port 131, which is then connected to feed line 135 via valve outlet port 133. The hydraulic fluid return line 136 is then interconnected via valve ports 134, 132 to reservoir return line 137. piston 98, the valve connections are interchanged such that feed line 128 interconnects to line 135 via valve ports 131, 134, and line 135 is interconnected to reservoir return line 137 via valve ports 133, 132. Gauge 138 indicates the hydraulic cylinder pressure, thereby permitting appropriate adjustment of the circuit control valves.

To reverse the motion of the hydraulic cylinderA Referring now to the rotary sweep movement, flow regulator bypass port 127 is connected via feed line 139 to valve 140, which is preferably of the same type as valve 127 of the transverse movement actuating circuit discussed above. Feed line 139 is connected via valve ports 141, 1113 to hydraulic line 14S interconnected to port 146 of rotary torque actuator unit 95. As connected in the manner shown in FIGURE 13, rotary torque actuator unit will translate in a counterclockwise direction as shown by the arrow. Port `147 of rotary torque actuating unit 95 is `connected to return line M8, which in turn is connected via valve ports 1114, 142 to reservoir return line 149. Reservoir return line 149 includes speed control 150, to maintain the proper angular speed of the drive means. To reverse the direction of rotary torque actuator movement, the valve 140 port connections are reversed, whereby feed line 139 feeds line `1% via ports 141 and 144, and the rotary torque actuator reservoir return line will be via lines 145 and valve ports 143, 142. To maintain control of the overall system, a feedback signal `from rotary scan line 145 is presented to pump 121, having pressure converter 151 and gauge 152.

The aforesaid hydraulic circuit provides a simplified system whereby simultaneous two-directional feed may be obtained, and the torque of one of said `feeds may be maintained by bleeding one line off the other during the stroke.

it is thus seen that my invention provides a simplified apparatus for the production bending of elongated members, such as aluminum tubing, by applying the tube against a backup form with a pressure-actuated follower. An easily adjustable backup form is provided to readily permit modification of the tube contour to be formed.

lt is naturally understood that various embodiments and modifications may be made to the above-described embodiment without departing from the spirit and scope of the invention, as for example the basic actuating means for the drive means may be modified in accordance with the particular material being bent, such as solid or tubular aluminum or steel bars; the manner of interconnecting the individual backup stops may also be modified to overcome the head pressure, Where it is increased for the bending of more rigid materials; the actual configuration of the individual stops and their manner of position adjustment may be modified; and although illustrated as bending parabolic tubes for antennas may be used for various other applications, such as the fabrication of tubular furniture, or automobile tailpipes.

In Ithe foregoing description, this invention has been described in conjunction with a preferred illustrative embodiment. Since many variations and modifications will now become apparent lto those skilled in the art, I prefer not to be limited to the specific disclosure herein but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

l. An article bending apparatus comprising a back up form having an enlogated surface of a predetermined contour; follower means operatively positioned to translate along a path established by said elongated surface; drive means operatively connected to said follower means and including power 'actuating means adapted to simultaneously move said follower means along said path, and force said follower means against said elongated surface with appreciable force; said follower means constructed to forcibly present an article to said elongated surface in a close relationship therewith, whereby the translation of said follower means along said path progressively urges the length of said article against said elongated surface; said drive means including an elongated arm motivating said follower means at the terminus thereof; said power actuating means moving said arm such that said follower means simultaneously sweeps the extent of said path and is radially varied to forcibly contact said elongated surface; said actuating means including a first ansiosi and second actuating member; said first actuating member forcibly rotating said arm about a first axis operatively positioned to sweep said follower along the extent of said path; said second actuating member forcibly providing transverse movement of said follower along the axis of said arm `to urge said follower towards said elongated surface; said transverse movement limited by the engagement of said follower and said elongated surface wherein; said first and second actuating members are interconnected to a common control circuit; said common central circuit providing a constant sweep motion substantially independent of the transverse movement of said arm.

2. An article bending apparatus comprising a platform; a plurality of longitudinal channels extending in a first direction along said platform; a plurality of back stops secured to said channels; adjacent surfaces of said back stops collectively forming an elongated surface; elongated means extending between said adjacent surfaces to establish a smooth path; said path having a contour corresponding to the contour to be formed of the article being bent; follower means adapted to translate said path while containing the cross section of said article; said follower means connected to and motivated by a longitudinal arm extending radially across said platform; said follower means secured to the terminus of said arm; actuating means simultaneously sweeping said arm about a first axis generally perpendicular to said platform, and transversely moving the follower means carried end of said arm along the longitudinal axis thereof to maintain forceful engagement between said follower and said path; thereby urging said article to assume the contour of said path; said path having a generally parabolic contour, means releasably securing said back stops to said channels; said securing means constructed to permit longitudinal movement of said back stops in said channels whereby the contour to be formed of said article being bent may be adjusted in accordance with the spring-back of said article; said actuating means comprising -a first and second hydraulically operated member; said first and second hydraulically operated members interconnected to a common control circuit; said common control circuit providing a constant sweep motion substantially independent of the transverse movement of said arm.

3. An article bending apparatus comprising a platform; a plurality of longitudinal channels extending in a first direction along said platform; a plurality of back stops secured to said channels; adjacent surfaces of said back stops collectively forming an elongated surface; elongated means extending between said adjacent surfaces to establish a smooth path; said path having a contour corresponding to the contour to be formed of the article being bent; follower means adapted to translate said path while containing the cross section of said article; said follower means connected to and motivated by a longitudinal arm extending radially across said platform; actuating means simultaneously sweeping said arm about a first axis generally perpendicular to said platform, and transversely moving the follower means carried end of said arm along the longitudinal axis thereof to maintain forceful engagement between said follower and said path; thereby urging said article to assume the contour of said path; said path having a generally parabolic contour, means releasably securing said back stops to said channels; said securing means constructed to permit longitudinal movement of said back stops in said channels whereby the contour to be formed of said article being bent may be adjusted in accordance with the spring-back of said article; said actuating means comprising a first and second hydraulically operated member; said first and second hydraulically ope-rated members interconnected to a common control circuit; said common control circuit providing a constant sweep motion substantially independent of the transverse movement of said arm; longitudinal arm formed of a plurality of individual said radially reciprccable sections removably fastened to vary the length of said arm in accordance with the contour of said path being swept; means clamping the end of said article against said elongated surface.

References Cited by the Examiner UNITED STATES PATENTS 328,986 10/85 Warwick 153-46 653,704- 7/00 Hightower et al. 153-45 1,353,168 9/20 McArthur 153-46 2,350,379 6/44 Weightman 153-46 2,663,349 12/53 Albrecht 153-46 2,881,530 4/59 Muller 33-177 FOREGN PATENTS 996,500 8/51 France.

615 1/ 15 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

WLLIAM I. STEPHENSON, Examiner. 

1. AN ARTICLE BENDING APPARATUS COMPRISING A BACK UP FORM HAVING AN ELONGATED SURFACE OF A PREDETERMINED CONTOUR; FOLLOWER MEANS OPERATIVELY POSITION TO TRANSLATE ALONG A PATH ESTABLISHED BY SAID ELONGATED SURFACE; DRIVEN MEANS OPERATIVELY CONNECTED TO SAID FOLLOWER MEANS AND INCLUDING POWER ACTUATING MEANS ADAPTED TO SIMULTANEOUSLY MOVE SAID FOLLOWER MEANS ALONG SAID PATH, AND FORCE SAID FOLLOWER MEANS AGAINST SAID ELONGATED SURFACE WITH APPRECIABLE FORCE; SAID FOLLOWER MEANS CONSTRUCTED TO FORCIBLY PRESENT AN ARTICLE TO SAID ELONGATED SURFACE IN A CLOSE RELATIONSHIP THEREWITH, WHEREBY THE TRANSLATION OF SAID FOLLOWER MEANS ALONG SAID PATH PROGRESSIVELY URGES THE LENGTH OF SAID ARTICLE AGAINST SAID ELONGATED SURFACE; SAID DRIVE MEANS INCLUDING AN ELONGATED ARM MOTIVATING SAID FOLLOWER MEANS AT THE TERMINUS THEREOF; SAID POWER ACTUATING MEANS MOVING SAID ARM SUCH THAT SAID FOLLOWER MEANS SIMULTANEOUSLY SWEEPS THE EXTENT OF SAID PATH AND IS RADIALLY VARIED TO FORCIBLY CONTACT SAID ELONGATED SURFACE; SAID ACTUATING MEANS INCLUDING A FIRST AND SECOND ACTUATING MEMBER; SAID FIRST ACTUATING MEMBER 